VOA慢速英语--Study: Modern Japanese Genetics Come from Three Ancient Groups

 Study: Modern Japanese Genetics Come from Three Ancient Groups

Scientists studying the genetic¹ material of Japanese people say that three ancient populations were ancestors of modern Japanese rather than two.

The research was published last week. It suggests that the genetic ancestry² of modern Japanese is more complex than experts had thought.

The researchers studied the genetic information of 17 ancient Japanese people. They took deoxyribonucleic acid, or DNA³, from the bones of 12 ancient people for the study. They also used earlier information from five other individuals. They then compared the DNA to that of modern Japanese people.

The research confirmed that there were two ancient groups of people in Japan. The first was an early group of hunter-gatherers. They first appeared between 20,000 and 15,000 years ago during what is called the Jomon period.

The second group is estimated to have first come from Northeastern Asia about 3,000 years ago. That group is believed to have brought modern rice farming methods to Japan during what is called the Yayoi period.

The researchers said these two groups are thought to be the main genetic ancestors of modern Japanese people.

But the researcher said they found that 71 percent of modern Japanese genetic ancestry comes from a third population that arrived about 1,700 years ago. The people of this period, known as the Kofun, are believed to have brought cultural ideas such as centralized leadership. These migrants had an ancestry similar to Han people in modern China.

Shigeki Nakagome was one of the leaders of the research published in Science Advances. He is with Trinity College Dublin in Ireland. He said, "We are very excited about our finds on the tripartite structure of the Japanese populations." He said the findings were important because they used the study of ancient genetic material to "rewrite the origins of modern Japanese."

Daniel Bradley is a co-leader of the research and is also with Trinity College Dublin. He said the ancient DNA showed ancestry in a way that could not be seen using modern genetic material.

The Kofun period is named for the large burial places made of earth that the people then built for their rulers. During that period, important technologies were arriving from China by passing through the Korean Peninsula.

"Chinese characters started to be used in this period, such as Chinese characters inscribed⁴ on metal implements⁶, for example swords," Nakagome said.

Scientists use the word implement⁵ to describe early weapons such as swords.

Japan is an island nation that includes thousands of islands. Its geography made migration⁷ in ancient times difficult. The first people are believed to have reached Japan when world sea levels were lower, more than 30,000 years ago.

The researchers said the genetics of Japan's population have not changed very much since the Kofun period, which lasted about 400 years.

Words in This Story

tripartite –adj. involving three people, groups, or parts

origin –n. the point or place where something begins or is created : the source or cause of something

characters –n. (pl.) a symbol (such as a letter or number) that is used in writing or printing

inscribed –adj. to place writing on an object often by cutting into the material itself

1 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

2 ancestry   

n.祖先，家世

参考例句：

• Their ancestry settled the land in 1856.他们的祖辈1856年在这块土地上定居下来。
• He is an American of French ancestry.他是法国血统的美国人。

3 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

4 inscribed   

v.写，刻( inscribe的过去式和过去分词 )；内接

参考例句：

• His name was inscribed on the trophy. 他的名字刻在奖杯上。
• The names of the dead were inscribed on the wall. 死者的名字被刻在墙上。 来自《简明英汉词典》

5 implement   

n.(pl.)工具，器具；vt.实行，实施，执行

参考例句：

• Don't undertake a project unless you can implement it.不要承担一项计划，除非你能完成这项计划。
• The best implement for digging a garden is a spade.在花园里挖土的最好工具是铁锹。

6 implements   

n.工具( implement的名词复数 )；家具；手段；[法律]履行（契约等）v.实现( implement的第三人称单数 )；执行；贯彻；使生效

参考例句：

• Primitive man hunted wild animals with crude stone implements. 原始社会的人用粗糙的石器猎取野兽。 来自《现代汉英综合大词典》
• They ordered quantities of farm implements. 他们订购了大量农具。 来自《现代汉英综合大词典》

7 migration   

n.迁移，移居，（鸟类等的）迁徙

参考例句：

• Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
• He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。